Perkos thru-hull connection features a plain cast bronze construction. The lange is machined to fit hull and grooved to retain bedding compound. The neck is threaded to approximately 3/16" from flange. Hose size: 3/4". Mounting hole diameter: 1". Maximum hull thickness: 1-5/8". Flange OD: 1-7/8". Not recommended for use below the waterline.